c2 the periodic table

John Dalton arranged the elements in order of atomic weight, which had been measured in various chemical reactions.

The Russion chemist Ditri Mendeleev arranged the 50 elements in order of their atomic weights. He left gaps for elements that had not yet been discovered. Then he used the table to predictwhat their properties should be. So when elements where discovered it matched his predictions, so this table was excepted by the scientific community.

The periodic table is named because of the regularly repeating patterns in the properties of elements.

The chemical elements are placed in order of their atomic (proton) number in the periodic table, so that the elements are arranged up in groups (vertical columns) with similar properties. Elements in the same group of the periodic table react in similar ways because their atoms have the ame number of electrons in their outermost shell. Elements in group 6 have 6 electrons in their outermost shell.

Metals conduct electricity but non-metals are electrical insulators. Metals have higer melting and boiling points.Non-metals are founf in the top right hang corner. Non-metals gain electrons to form negative ions, The atoms of metals lose electrons to form a positive ion.

Noble gases have eight electrons in their outermost shell, mking the atoms very stable. They are very unreactive because of their very stable electron arrangements.

Group 1 and 2 are knows as the reactive metals, these metals react vigorously with water, are soft .

Lithium, sodium,potassium,rubidium,caesium and francium. All alkali metals are very reactive. They have to be stored in oil, which stops it reacting with oxygen in the air. Th reactivity increases as you go down the group. So lithium is the least reactive alkali and francium is the most reactive.

All alkali metals have very low density, so they float in water. The metals are very soft and can be cut with a knife. They have a silvery shiny surface when you first cut them, but quickly goes dull  as the metals react with oxygen in the air. This forms a layer of oxide on the shiny surface.

Going down the group, melting and boiling points get lower and lower. When you add lithim,sodium or potassium with ater, the metal floats on the water, moving around and fizzing. This is because a metal hydroxideis formed and hydrogen gas is given off

Alkali metals react with non-metals to form ionic compounds, the metal ion loses one electron to form a metal ion with a positive charge.

They have seven electrons in their outermost shell. The halogens consists of molecules made up of pairs of atoms.

Reactivity decreases down the group becase the outer shell gets further away from the nucleus, so its ess easy to gain a electron. The further down group 7 the element is, then the higher its relative molecular mass (melting point and boiling point).

Halogens react with metals to produce ionic salts, When this happens, the halogen atoms gains one electron to form a halide ion with a negatie charge.

A more reactive halogen will displace a less reactive halogen from an aqueous solution of its salt. For example, chlorine will displace bromine from potassium bromide and iodine from pottasium iodide. Bromine will displace iodine from pottasium iodide.

The transition metals are in the centre of the periodic table, between groups 2 and 3.

They form coloured compounds. Copper sulfate is blue. Nickel carbonate is pale green. Chromium oxide is dark green. Magnese chloride is pale pink.

They have ions with different charges

They can be used as catalysts to speed up chemical reactions

Like all other metas, transition metals are good conductors of heat and electicity and can be easily hammered into shape. They are hard and strong, they have high densities.

The transition metals are much less reactive than the metals in group 1. They do not react eadily with oxygen, chloring, or water as alkali metals do.